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Date:   Mon, 27 Feb 2023 09:52:21 +0100
From:   Johan Hovold <johan@kernel.org>
To:     Dan Carpenter <error27@gmail.com>
Cc:     linux-serial@vger.kernel.org
Subject: Re: [bug report] serial: 8250: fix handle_irq locking
Message-ID: <Y/xvRQSmS67sv2cL@hovoldconsulting.com>
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On Mon, Feb 27, 2023 at 10:16:30AM +0300, Dan Carpenter wrote:
> Hello Johan Hovold,
> 
> The patch 853a9ae29e97: "serial: 8250: fix handle_irq locking" from
> Jul 14, 2021, leads to the following Smatch static checker warning:
> 
> drivers/tty/serial/8250/8250_fsl.c:84 fsl8250_handle_irq() warn: inconsistent returns 'flags'.
>   Locked on  : 38,46
>   Unlocked on: 84
> 
> drivers/tty/serial/8250/8250_fsl.c
>     26  int fsl8250_handle_irq(struct uart_port *port)
>     27  {
>     28          unsigned long flags;
>     29          u16 lsr, orig_lsr;
>     30          unsigned int iir;
>     31          struct uart_8250_port *up = up_to_u8250p(port);
>     32  
>     33          spin_lock_irqsave(&up->port.lock, flags);
>                                                   ^^^^^
>     34  
>     35          iir = port->serial_in(port, UART_IIR);
>     36          if (iir & UART_IIR_NO_INT) {
>     37                  spin_unlock(&up->port.lock);
>     38                  return 0;
> 
> Needs to enable IRQs again.  Same below etc.

Thanks, Dan. I just sent a fix here:

	https://lore.kernel.org/r/20230227085046.24282-1-johan@kernel.org

Johan